Fluid dispensers are well known for dispensing hand cleaning fluids as may be provided, for example, in washrooms and hospitals. Examples of such dispensers include those disclosed in U.S. Patent Publication US 2008/0121663 to Ophardt et al, published May 29, 2008; U.S. Patent Publication US 2010/0288788 to Ophardt published Nov. 18, 2010; U.S. Patent Publication US 2011/0017769 to Ophardt published Jan. 27, 2011; U.S. Patent Publication US 2007/0158363 to Ophardt published Jul. 12, 2007 and U.S. Patent Publication US 2010/0147879 to Ophardt et al published Jun. 17, 2010, the disclosures of which are incorporated herein by reference. With such dispensers, as fluid from the reservoir bottle is used up, the fluid needs to be replaced as by removing and replacing an empty bottle with a bottle which is filled with fluid.
Previously known automated mechanisms for determining the fluid level in the reservoir bottle include counters to count the number of times that a dispensing mechanism is activated and calculating with an estimation of the approximate dosage of each activation, the fluid dispensed to determine when a bottle of a given volume may be considered empty. Such prior art mechanisms suffer the disadvantage that they require monitoring of the volume of fluid in each bottle, monitoring of removal and attachment of a bottle and maintaining a count of the number of activations in order to estimate when a bottle is empty. Such arrangements have been found to be disadvantageous notably in manually operated dispensers as requiring an arrangement for the counting mechanism to be coupled to the pump mechanism. Such arrangements also have the disadvantageous in manually operated and automatic dispensers in requiring recognition as to when a bottle has been coupled to the dispenser, and recognition when a bottle that is coupled to the dispenser is full so as to represent an initiation point for counting. Such arrangements have been found to be disadvantageous in providing a requirement for having bottle sensing arrangements separate from mechanisms which may recognize the activation of the pump.